A “MOF-Protective-Pyrolysis” Strategy for the Preparation of Fe–N–C Catalysts and the Role of Fe, N, and C in the Oxygen Reduction Reaction in Acidic Medium

Abstract

M–N–C electrocatalysts for the oxygen reduction reaction (ORR) have been considered as the most promising alternatives to precious metal catalysts. However, the catalytic activity of M–N–C especially in an acidic medium is still unable to meet the practical requirement, and the corresponding ORR mechanism also remains unclear. Herein, an “MOF-protective-pyrolysis” strategy was adopted to synthesize an Fe–N–C catalyst (P-FeMOF@ZIF-8) with Fe–N4 as the predominant Fe species. The P-FeMOF@ZIF-8 displays high catalytic activity in both acidic and alkaline mediums. The experimental results further reveal the different importance of the Fe species in different mediums. Based on the results, a distinct mechanism of the ORR the in acidic medium was proposed, where the synergistic effect of the Fe–N4 site and carbon in improving the kinetics of the ORR were well explained. The findings and the corresponding perspective may provide a new guidance for the design of highly efficient ORR electrocatalysts.

Synthesis and Performance of MOF-Based Non-Noble Metal Catalysts for the Oxygen Reduction Reaction in Proton-Exchange Membrane Fuel Cells: A Review

“…Wang et al [ 67 ] introduced an “MOF-protective-pyrolysis” strategy for the preparation of Fe-N-C catalysts, in which NH 2 -MIL-101-Fe (FeMOF) with a regular structure was selected as an Fe source, while the ZIF-8 shell acted as a protective layer and a source of carbon and nitrogen. TEM images acquired after pyrolysis revealed that the octahedral FeMOF was still well surrounded by ZIF-8 and that carbon nanotubes grew on the surface of the pyrolyzed material.…”

Core‐shell FeCo N‐doped biocarbons as stable electrocatalysts for oxygen reduction reaction in fuel cells

“…[4][5][6] In the recent years, investigations on the low cost, highly active and stable non-noble catalysts [7][8][9][10] for fuel cells were comprehensively carried out. According to the earlier reports, 9,[11][12][13][14][15][16][17][18][19] the development of M-N-C (M = transition metals) catalysts was shown to be very promising toward ORR. Particularly, the synergy of bimetal catalysts with more active and stable sites was reported to exhibit surpassing ORR.…”

Synthesis of a Zn/Fe–N–C electrocatalyst towards efficient oxygen reduction reaction via a facile one-pot method

“…Metal-organic frameworks (MOFs) have the advantages of uniform distribution of metal particles, large SSA and abundant pore structures, and are good precursors for the synthesis of M-N-C catalysts [35][36][37][38]. However, the commonly used MOFs are mainly ZIF-8, ZIF-67, and MIL-101, which limits the diversity of material development to some extent [39][40][41]. In addition, the preparation and modification of these MOFs are complicated and usually involve the use of large amounts of organic solvents.…”